National Repository of Grey Literature 60 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Aplikace environmentální rastrovací elektronové mikroskopie (EREM) v oboru analýzy miniatur: metodika pro specifické použití ve výzkumu miniaturního malířství
Hradil, David ; Hradilova, Janka ; Neděla, Vilém ; Tihlaříková, Eva
The methodology deals with a completely new, unused procedure of non-invasive analysis of painted portrait miniatures, using environmental scanning electron microscope with an energy-dispersive X-ray spectrometer (ESEM-EDS). ESEM, unlike the conventional scanning electron microscope (SEM), allows the analysis of the painting on the ivory support, which is not possible in the gas pressure approaching the vacuum, where there is a risk of deformation and damage due to the drying of this biological material. Instead of an inert gas (nitrogen, argon), the aim is to use a mixture of nitrogen and water vapor at a defined pressure corresponding to the required relative humidity in the measuring chamber. This enables a completely non-invasive analysis of painted miniature objects on organic types of supports. This methodology is divided into two parts: morphological analysis and elemental composition analysis. The first case involves the study of morphological details at high magnification (e. g. the possibility of distinguishing different types of supports or characterizing their microstructure). The second part describes the implementation of elemental analysis in high spatial resolution (distinction of individual pigment grains).
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SMV-2021-04: Advanced EDX analysis of miniature painting in ESEM
Neděla, Vilém ; Tihlaříková, Eva
Samples were analysed in experimentally reached and optimised high pressure conditions of environmental scanning electron microscope and using EDS X-Ray micro-analyser.
SMV-2020-22: Morphological analysis of miniature painting using light microscopy and ESEM
Neděla, Vilém
Miniature painting were analysed in experimentally reached and optimised high pressure conditions of environmental scanning electron microscope and using light microscopy. Optimal gas pressure and humidity were set to minimise sample damage. Special detectors were used for low dose imaging of surface morphology.
SMV-2020-21: Elemental X-Ray analysis of miniature painting using ESEM
Neděla, Vilém
Miniature painting were analysed in experimentally reached and optimised high\npressure conditions of environmental scanning electron microscope and using EDS X-Ray micro-analyser.
SMV-2019-12: Morphological analysis of miniature painting
Neděla, Vilém
Miniature painting were analysed in experimentally reached and optimised high pressure conditions of environmental scanning electron microscope and using light microscopy. Optimal gas pressure and humidity were set to minimise sample damage. Special detectors were used for low dose imaging of surface morphology.
SMV-2019-11: Elemental X-Ray analysis of miniature painting
Neděla, Vilém
Miniature painting were analysed in experimentally reached and optimised high pressure conditions of environmental scanning electron microscope and using EDS X-Ray micro-analyser.
In vivo study of diatom assemblages using low temperature method for ESEM
Tihlaříková, Eva ; Neděla, Vilém ; Fránková, Markéta
Diatoms are the most species-rich algal group represented by 12 000 described species and are recognized as powerful bio indicators and used for water quality monitoring. Diatom taxonomy is predominantly based on the morphology of ornate silicified cell wall called frustule composed of two overlapping parts (thecae). This frustule displays intricate patterns and designs unique to each species. For these studies conventional scanning electron microscopy (SEM) was and still is widely used. This method requires cleaning of diatom frustules in strong acids and peroxides followed by conductive coating.This aggressive procedure removes protoplast and damages delicate structures. Environmental scanning electron microscopy (ESEM) brings advantages of observation of fresh diatom material that are presence of whole intact diatom cells, not only empty diatom frustules, extracellular mucilaginous diatom secrets (e.g. pads, stalks, tubes) and whole diatom assemblages directly in situ together with other algal assemblages (e.g. cyanobacteria or green algae). However, in diatom research, ESEM is used mainly for elimination of conductive coating and observation of these organisms in their native wet state adhered directly on the host plant is not yet common. The ESEM observation of native aquatic samples is usually affected with radiation damage that can be lovered by the use of special methods like the Low Temperature Method (LTM) for the ESEM.
Optimization of scintillation detector for detection of low energy signal electrons in electron microscopy
Tihlaříková, Eva ; Kadlec, Jaromír (referee) ; Uruba, Václav (referee) ; Neděla, Vilém (advisor)
The dissertation thesis deals with optimization of the scintillation detector for efficient detection of low energy signal electrons in a specimen chamber of a scanning electron microscope. The solution was based on the study of signal electron energy loss mechanisms during their interaction with a conductive layer and a scintillator that can be studied using simulations based on the stochastics Monte Carlo methods. Based on test simulations and their comparison with experimental data, the ideal Monte Carlo software was chosen and used for the study of signal electron energy losses during their transport through the conductive layer as well as following interaction with scintillator, in dependency on the signal electron energy. Simulation results allowed to define criteria for the optimization of the conductive layer. According to these parameters, the optimized layers were deposited on the surface of different scintillators and experimentally tested in the scintillation detector of the scanning electron microscope. Experimental measurements allowed to verify accomplished simulations and provide new information about impact of materials and thicknesses of conductive layers in combination with materials of scintillators and light guides. The increase of the detection efficiency of the scintillation detector equipped with optimised conductive layers and its capability to detect low energy signal electrons were experimentally proved.
Detection of Signal Electrons in High Pressure Conditions in Environmental Scanning Electron Microscopy
Neděla, Vilém ; Jirák, Josef (advisor)
The thesis deals with the study of properties of a new system for detection of true secondary and backscattered electrons in high pressure conditions of the specimen chamber of a newly built environmental scanning electron microscope AQUASEM II. Detection system contains three detectors. For the first time is introduced and analyzed the working principle of ionisation detector with electrostatic separator, which is in many experiments compared with ionisation detector of secondary electrons. Experimentally demonstrated are unique properties of this detection system, especially the ability of energy separation of detected signal electrons. For the various working conditions are also analyzed signal levels detected by the BSE YAG detector, which is designed as a part of the new detection system and which worked together with both ionisation detectors.
Scintillation SE Detector with Controlled Gas Flow for VP SEM
Kozák, Josef ; Neděla, Vilém (referee) ; Jirák, Josef (advisor)
This master’s thesis deals with a design and optimization of an experimental scintillation secondary electron detector for the environmental scanning electron microscope and with a description of a detector operation principle. The experiment is founded on simulations of a gas flow in detector inner sections and on simulations of secondary electron trajectories in electrostatic fields of the detector. On the basis of the simulations, new solutions of the detector designs are proposed. For these designs, same simulations as previous are performed and designs that seem to be feasible for the secondary electron detection in environmental scanning electron microscope are selected.

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